In the United States, non-Hodgkin's lymphoma incidence rates have risen 3 percent per year for four decades, and non-Hodgkin's lymphoma mortality 1.6 percent compared with 0.2 percent for all cancers combined. An analysis of trends in both sexes and around the world suggests that the rise may be due to an etiologic agent(s) that has become increasingly prevalent in the general environment. Based on studies showing increased risk of non-Hodgkin's lymphoma among farmers exposed to pesticides, we are investigating risk that may be associated with environmental pesticide exposures. In a multi-disciplinary case-control study of non-Hodgkin's lymphoma, we are measuring pesticides in household dusts, serum samples, and tap water, as well as collecting questionnaire data on history of residential pesticide use. We are also examining the possible role of viruses, such as HTLV-1, HHV-6, HHV-8, and EBV, and assessing immune-related medical conditions and treatments, sunlight exposure, diet, hair dye use, and other hypothesized risk factors. Analytic approaches are being developed to synthesize data collected from biospecimens, environmental samples, and computer-assisted questionnaires.